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From <...@covalent.net>
Subject Re: [VOTE] ap_r* model.
Date Fri, 02 Mar 2001 23:33:53 GMT

Cool.

Can I ask a stupid question.  How are we handling the out-of-order problem
for filters?  Are filters not expected to use functions for generating
data?  Could somebody please tell me why we are solving a problem for
handlers, and ignoring it completely for filters?  The exact same problem
exists.

Ryan

On Fri, 2 Mar 2001, Bill Stoddard wrote:

> Sorry Ryan, I am changing my vote too.   Based entirely on the discussion
> unfortunately...  The fewer opportunities we open for module authors to
> muck-up the better off we'll be.  Pragmatic wins over Philosophy.
>
> Add my vote to the OLD_WRITE filter tally.
>
> Bill
>
> ----- Original Message -----
> From: Greg Stein <gstein@lyra.org>
> To: <new-httpd@apache.org>
> Sent: Friday, March 02, 2001 4:21 PM
> Subject: Re: [VOTE] ap_r* model.
>
>
> > On Fri, Mar 02, 2001 at 09:19:15AM -0600, William A. Rowe, Jr. wrote:
> > > From: <rbb@covalent.net>
> > > Sent: Friday, March 02, 2001 9:04 AM
> > >
> > >
> > > > I think I remember gstein writing...
> > > >
> > > > > happen", but can only happen by a deliberate action of a module
> author. They
> > > > > have to take special measures to get themselves in front of OLD_WRITE.
> We
> > > > > don't have to take precautions against deliberate troublemakers;
there
> are
> > > > > too many other ways that a module author can screw things up.
> > > >
> > > > The problem isn't me as a module author, it is the other guy.  My module
> > > > may be fine, but what if there is another module that isn't.
> > >
> > > Here's the upshot.
> > >
> > > OLD_WRITE filter can be blown away not paying attention to filter
> ordering.
> >
> > OLD_WRITE just stops optimizing. It doesn't break.
> >
> > > r->bb can be blown away by anyone not paying attention to the request's
> own brigade.
> > >
> > > Which of these is harder to debug ?!?  Harder to document ?!?  That's the
> key!
> > >
> > > [We aren't talking about buckets here guys... the -brigade- is that stream
> that
> > > is sent down the filter stack.  I have yet to be convinced we need more
> than one
> > > per request.  As FirstBill and rbb point out, you just keep adding to it.]
> > >
> > > I see ordering problems as the hardest headache to debug.  r->bb
> misordering is
> > > fairly straightforward - if you start misordering, the module _author_
> messed up.
> > > If you have a filtering problem, the user will have some impact on filter
> ordering.
> > > That means they can create a problem.  If it's a choice between the module
> author
> > > and the end user creating bugs, I'll take the author's bugs any day.
> >
> > The OLD_WRITE scheme *never* has ordering problems. Ever.
> >
> > The only possible problem is that it won't be used. But that only happens if
> > the module author deliberately inserts their filter ahead of OLD_WRITE.
> > Explicit code to do it. The user can't make it happen.
> >
> > Harder to debug? OLD_WRITE won't cause ordering problems. Document?
> > OLD_WRITE would be classified as AP_FTYPE_INTERNAL. The doc on the filter
> > types states that module authors should never use that, or insert in front
> > of it. When a module author goes to figure out which type they want, it is
> > immediately obvious to steer clear.
> >
> > r->bb can cause ordering bugs. There is no point in the documentation to
> > describe the gotchas of synchronization and misordering.
> >
> > Cheers,
> > -g
> >
> > --
> > Greg Stein, http://www.lyra.org/
> >
>
>


_______________________________________________________________________________
Ryan Bloom                        	rbb@apache.org
406 29th St.
San Francisco, CA 94131
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